/*
 * 933_str_field_cap_run — runtime coverage for the C4.6 fold: reading a
 * str-typed FIELD of a struct (N_DOT value read) must load the full 24B
 * {ptr,len,cap} header, not just {ptr,len}. str is 24B since Phase 2 (#1);
 * pre-C4.6 the N_DOT str-field arms loaded 2 words and dropped cap.
 *
 * The byte-id gates (990-997) can't catch a symmetric 2-word miscompile:
 * if both stages drop cap identically, byte-id passes silently. So this
 * pins the *runtime* contract — build each fixture through both the cstage
 * `ww` and the wwstage `ww_ww` driver and confirm the assertions hold
 * (exit 0). The global row is the load-bearing case: in ww the global
 * struct-field load is a separate arm with no slice sibling (cstage folds
 * local+global in one base_reg arm; ww splits them), so a cap-drop there
 * would hide from the local-field rows.
 *
 * Each row POISONS the source str so cap != len (a `.cap =` pseudo-field
 * write, no malloc / no import — self-contained, so ww_ww writes
 * intermediates only next to the /tmp source). A 2-word field read leaves
 * cap = stale, so the read-back .cap mismatches the poison and the row
 * fails. The cap word is observed through `let s: str = <field>` (a 3-word
 * copy into the slot) then `s.cap` (an N_IDENT pseudo-field read off the
 * slot) — mirrors the 932 observation shape.
 *
 * Sites (C4.6 S1 + S2, case A):
 *   - s1local  : `st.f` — direct struct local field (base BP).
 *   - s1global : `g.f`  — direct struct global field (base CX).
 *   - s2ptr    : `pst.f` — field via a *struct local (base BX, deref).
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/wait.h>

static int
runwait(const char *cmd)
{
	int rc = system(cmd);
	if (rc == -1) return -1;
	if (WIFEXITED(rc)) return WEXITSTATUS(rc);
	return -1;
}

struct row { const char *label; const char *src; int want; };

static const struct row rows[] = {
	/* S1 local — `st.f` direct struct local field. Poison cap=8
	 * (len=2). spoil() interposes a call between the field store and
	 * the read: a call clobbers caller-saved CX, so a broken 2-word
	 * read leaves cap = spoil's leftover (44), not the lingering store
	 * value — without it CX would coincidentally still hold the poison
	 * the `st.f = p` store left behind and the row wouldn't discriminate. */
	{ "s1local_field",
	  "type rec = struct { f: str };\n"
	  "fn spoil() i32 = {\n"
	  "    let z: str = \"zzzz\";\n"
	  "    z.cap = 44i32;\n"
	  "    let w: str = z;\n"
	  "    return w.cap: i32;\n"
	  "};\n"
	  "export fn main() i32 = {\n"
	  "    let p: str = \"hi\";\n"
	  "    p.cap = 8i32;\n"
	  "    let st: rec;\n"
	  "    st.f = p;\n"
	  "    let junk: i32 = spoil();\n"
	  "    let s: str = st.f;\n"
	  "    if (s.cap: i32 != 8) { return 1; };\n"
	  "    if (s.len: i32 != 2) { return 2; };\n"
	  "    if (junk != 44) { return 3; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
	/* S1 global — `g.f` direct struct global field (base CX path).
	 * The no-local-sibling arm in ww; poison cap=9 (len=5). */
	{ "s1global_field",
	  "type rec = struct { f: str };\n"
	  "let g: rec;\n"
	  "export fn main() i32 = {\n"
	  "    let p: str = \"world\";\n"
	  "    p.cap = 9i32;\n"
	  "    g.f = p;\n"
	  "    let s: str = g.f;\n"
	  "    if (s.cap: i32 != 9) { return 1; };\n"
	  "    if (s.len: i32 != 5) { return 2; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
	/* S2 case A — `pst.f` field via a *struct local (deref, base BX).
	 * Poison cap=7 (len=3). */
	{ "s2ptr_field",
	  "type rec = struct { f: str };\n"
	  "export fn main() i32 = {\n"
	  "    let p: str = \"abc\";\n"
	  "    p.cap = 7i32;\n"
	  "    let st: rec;\n"
	  "    st.f = p;\n"
	  "    let pst: *rec = &st;\n"
	  "    let s: str = pst.f;\n"
	  "    if (s.cap: i32 != 7) { return 1; };\n"
	  "    if (s.len: i32 != 3) { return 2; };\n"
	  "    return 0;\n"
	  "};\n",
	  0 },
};

static int
run_driver(const char *driver, const struct row *r, int i)
{
	char src[96], tmpdir[96], cmd[1024];
	snprintf(src, sizeof src, "/tmp/strfieldcap_%d_%d.ww", getpid(), i);
	snprintf(tmpdir, sizeof tmpdir, "/tmp/strfieldcap_%d_d_%d", getpid(), i);

	FILE *f = fopen(src, "wb");
	if (!f) return -1;
	fputs(r->src, f);
	fclose(f);

	mkdir(tmpdir, 0755);
	snprintf(cmd, sizeof cmd, "cd %s && %s build %s",
	    tmpdir, driver, src);
	if (runwait(cmd) != 0) {
		fprintf(stderr, "row[%s]: build via %s failed\n",
		    r->label, driver);
		unlink(src); rmdir(tmpdir);
		return -1;
	}

	const char *base = strrchr(src, '/');
	base = base ? base + 1 : src;
	char outbin[160];
	snprintf(outbin, sizeof outbin, "%s/%s", tmpdir, base);
	char *dot = strrchr(outbin, '.');
	if (dot && strcmp(dot, ".ww") == 0) *dot = '\0';
	int got = runwait(outbin);

	unlink(src); unlink(outbin); rmdir(tmpdir);
	return got;
}

int
main(void)
{
	const char *bin = getenv("BIN");
	if (!bin) bin = "out/bin";
	char absbin[512];
	if (bin[0] != '/') {
		char cwd[256];
		if (getcwd(cwd, sizeof cwd) == NULL) return 1;
		snprintf(absbin, sizeof absbin, "%s/%s", cwd, bin);
		bin = absbin;
	}

	char cdrv[640];
	snprintf(cdrv, sizeof cdrv, "%s/ww", bin);
	char wdrv[640];
	snprintf(wdrv, sizeof wdrv, "%s/ww_ww", bin);

	struct { const char *name; const char *path; int gated_on_existence; }
	drivers[] = {
		{ "cstage",  cdrv, 0 },
		{ "wwstage", wdrv, 1 },
		{ NULL, NULL, 0 },
	};

	int n = (int)(sizeof rows / sizeof rows[0]);
	int total = 0, fail = 0;
	for (int d = 0; drivers[d].name; d++) {
		if (drivers[d].gated_on_existence
		    && access(drivers[d].path, X_OK) != 0) {
			fprintf(stderr,
			    "str_field_cap_run: skip %s (no %s)\n",
			    drivers[d].name, drivers[d].path);
			continue;
		}
		for (int i = 0; i < n; i++) {
			int got = run_driver(drivers[d].path, &rows[i], i);
			total++;
			if (got != rows[i].want) {
				fprintf(stderr,
				    "str_field_cap_run[%s][%s]: exit=%d want=%d\n",
				    drivers[d].name, rows[i].label,
				    got, rows[i].want);
				fail++;
			}
		}
	}

	if (fail) {
		fprintf(stderr, "str_field_cap_run: %d/%d fixtures failed\n",
		    fail, total);
		return 1;
	}
	printf("str_field_cap_run: %d/%d ok\n", total, total);
	return 0;
}